Medical image processing apparatus, medical image processing method, computer-readable medical-image processing program, moving-object tracking apparatus, and radiation therapy system

ABSTRACT

A medical image processing apparatus comprising: a first input interface configured to acquire a three-dimensional volume image of an object which is provided with at least one marker, the three-dimensional volume image being generated by imaging the object using a medical examination apparatus; a second input interface configured to acquire geometry information of an imaging apparatus which is used for imaging the object to generate a fluoroscopic image of the object; and a specific-setting-information generator configured to generate specific setting information based on the three-dimensional volume image and the geometry information, the specific setting information being used for setting of imaging for generating an image depicting the at least one marker or setting of image processing of the image depicting the at least one marker.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of Japanese PatentApplication No. 2016-226133, filed on Nov. 21, 2016, the entire contentsof which are incorporated herein by reference.

FIELD

Embodiments of the present invention relates to medical image processingtechnology to process a medical image used for a radiation therapysystem.

BACKGROUND

Conventionally, when an affected part (i.e., lesion area) of a patientis irradiated with radioactive rays as treatment, the affected partmoves in some cases due to movement of the patient such as breathing,heartbeat, and/or intestinal movement. Thus, the affected part isirradiated with radioactive rays under a gated irradiation method usinga metal marker or a tracking irradiation method. For instance, byimaging a patient with the use of X-rays during treatment, afluoroscopic image depicting the marker placed in the vicinity of theaffected part is obtained. The movement of the marker is tracked bymatching the fluoroscopic image with a template such that the affectedpart is irradiated at an appropriate timing.

[Patent Document 1] Japanese Unexamined Patent Application PublicationNo. 2000-167072

In the above-described technique, a user such as a doctor and/or aradiological technician has to set the template while referring to thefluoroscopic image of the patient whose X-ray images are preliminarilygenerated during treatment planning, which takes time and effort.Further, when the entire range of the fluoroscopic image is processed ona real-time basis in the case of tracking the position of the marker byperforming image processing on the fluoroscopic image during treatment,processing load of the CPU increases. Thus, a user has to previously setthe range in which the marker is depicted in the fluoroscopic image inorder to reduce the load of image processing, and there is a problemthat it takes time and effort.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a system configuration diagram illustrating the radiationtherapy system of the first embodiment;

FIG. 2 is a block diagram illustrating the medical image processingapparatus of the first embodiment;

FIG. 3 is a block diagram illustrating the moving-object trackingapparatus of the first embodiment;

FIG. 4 is a schematic diagram illustrating relationship between X-rayirradiators, X-ray detectors, and a patient;

FIG. 5 is a schematic diagram illustrating an X-ray image (DRR image)used for tracking a marker;

FIG. 6 is a schematic diagram illustrating an X-ray image (DRR image)used for selecting a marker;

FIG. 7 is a schematic diagram illustrating an X-ray image (DRR image)when a range notification is changed;

FIG. 8 is another schematic diagram illustrating an X-ray image (DRRimage) when a range notification is changed;

FIG. 9 is a flowchart illustrating the anterior part of thespecific-setting-information generation processing to be performed bythe medical image processing apparatus;

FIG. 10 is a flowchart illustrating the posterior part of thespecific-setting-information generation processing to be performed bythe medical image processing apparatus;

FIG. 11 is a flowchart illustrating the anterior part of the markertracking processing to be performed by the moving-object trackingapparatus of the first embodiment;

FIG. 12 is a flowchart illustrating the posterior part of the markertracking processing to be performed by the moving-object trackingapparatus of the first embodiment;

FIG. 13 is a block diagram illustrating the moving-object trackingapparatus of the second embodiment;

FIG. 14 is a flowchart illustrating the anterior part of the interlockprocessing to be performed by the moving-object tracking apparatus;

FIG. 15 is a flowchart illustrating the posterior part of the interlockprocessing to be performed by the moving-object tracking apparatus;

FIG. 16 is a block diagram illustrating the moving-object trackingapparatus of the third embodiment;

FIG. 17A is a schematic diagram illustrating marker images;

FIG. 17B is a schematic diagram illustrating non-marker images; and

FIG. 18 is a flowchart illustrating the marker tracking processing to beperformed by the moving-object tracking apparatus of the thirdembodiment.

DETAILED DESCRIPTION

In one embodiment of the present invention, a medical image processingapparatus comprising: a first input interface configured to acquire athree-dimensional volume image of an object which is provided with atleast one marker, the three-dimensional volume image being generated byimaging the object using a medical examination apparatus; a second inputinterface configured to acquire geometry information of an imagingapparatus which is used for imaging the object to generate afluoroscopic image of the object; and a specific-setting-informationgenerator configured to generate specific setting information based onthe three-dimensional volume image and the geometry information, thespecific setting information being used for setting of imaging forgenerating an image depicting the at least one marker or setting ofimage processing of the image depicting the at least one marker.

First Embodiment

Hereinafter, embodiments will be described with reference to theaccompanying drawings. First, the medical image processing apparatus ofthe first embodiment will be described with reference to FIG. 1 to FIG.12. The reference sign 1 in FIG. 1 denotes a radiation therapy systemused for radiotherapy, in which a lesion area T such as a tumorgenerated in a body of a patient P is irradiated with radioactive raysR. The radioactive rays R used for treatment include, e.g., X-rays,y-rays, electron beams, proton beams, neutron beams, and heavy particlebeams.

When radiotherapy is performed, the radioactive rays R with sufficientoutput must be accurately radiated onto the position of the lesion areaT (i.e., target area) of the patient (object) P. Further, it isnecessary to suppress exposure dose of normal tissues (non-target area)in the vicinity of the lesion area T. In the treatment of visceralcancer such as lung cancer, liver cancer, and pancreatic cancer, thelesion area T is always moving together with motion such as breathing,heartbeat, and intestinal motion. Among plural irradiation methods, inthe gating irradiation method, the irradiation position and theirradiation range of the radioactive rays R are fixed in advance. Thus,it is necessary to grasp the movement of the lesion area T and toradiate the radioactive rays R at the timing when the lesion area T isat a specific position. In the tracking irradiation method, the positionof the lesion area T is tracked and the radioactive rays R are radiatedonto the lesion area T specified by the tracking processing. In thefollowing, a description will be given of cases of the gatingirradiation. However, the present invention can also be applied to thetracking irradiation method. For specifying the position of the lesionarea T, for instance, an X-ray image is used. However, the lesion area Tis not necessarily clearly depicted in the X-ray image.

For this reason, in the present embodiment, a marker M (FIG. 4) isplaced in the vicinity of the lesion area T. This marker M appears moreclearly than the lesion area T. Since this marker M moves synchronouslywith the movement of the lesion area T, the movement of the lesion areaT is grasped by imaging and monitoring the movement of the marker Musing X-rays. Afterward, the radioactive ray R are radiated at a timingwhen a predetermined irradiation condition is satisfied. For instance,the irradiation condition is such a timing that the patient P exhales(i.e., breathes out) and the marker M comes to a specific position, andthe radioactive rays R are repeatedly radiated onto the lesion area T insynchronization with respiration of the patient P. Although radiation ofthe radioactive rays R in synchronization with respiration isexemplified in the following description, the radioactive rays R may beradiated in synchronization with other motion of the patient P such asheartbeat and intestinal motion.

The marker M of the present embodiment is composed of, e.g., a minutemetal ball having a diameter of approximately 1 to 2 mm. A materialwhich is harmless even in the case of being placed or indwelled in thebody is used as the material of the marker M. For instance, gold isused. Since metal is a material harder to transmit X-rays than tissuesconstituting a human body, metal is relatively clearly depicted in anX-ray image 40 (FIG. 5 to FIG. 8). In addition, the marker M is insertedinto the body by using a dedicated puncture instrument such as anintroducer (needle guide). For instance, plural markers M1 to M3 areplaced in the vicinity of the lesion area T in the body (FIG. 4).

As shown in FIG. 1, in the case of preparing a treatment plan using theradiation therapy system 1, firstly, computed tomography is performed onthe patient (object) P in which the marker M is placed. In the presentembodiment, a medical examination apparatus 2 for performing variousexaminations of the patient P by computed tomography is provided. Thismedical examination apparatus 2 is configured as an X-ray CT (ComputedTomography) apparatus. A three-dimensional volume image of the patient Pis generated by using the medical examination apparatus 2. Thethree-dimensional volume image is composed of, e.g., voxel data.

Although an X-ray CT apparatus is exemplified in the present embodiment,the medical examination apparatus (diagnostic apparatus) 2 may beanother type of diagnostic apparatus as long as it can acquire athree-dimensional volume image of the patient P. For instance, themedical examination apparatus 2 may be configured as an MRI (MagneticResonance Imaging) apparatus or an ultrasonic diagnostic apparatus.

The radiation therapy system 1 of the present embodiment includes amedical image processing apparatus 3, an X-ray imaging apparatus 7(i.e., fluoroscopic imaging apparatus), a respiration monitoringapparatus 8, a moving-object tracking apparatus 4, a radiationirradiation apparatus 5, and a bed 6 on which the patient P is placed.The medical image processing apparatus 3 generates specific settinginformation used for setting of imaging for generating an imagedepicting the marker M or setting of image processing of this image. TheX-ray imaging apparatus 7 serially (i.e., sequentially) images thepatient P so as to generate the X-ray images (fluoroscopic images) 40 inwhich the lesion area T of the patient P and the marker M are depicted.The respiration monitoring apparatus 8 monitors respiration of thepatient P. The moving-object tracking apparatus 4 tracks (i.e., traces)the position of the marker M which moves every moment, by using thespecific setting information and each X-ray image 40. The radiationirradiation apparatus 5 irradiates the lesion area T with radioactiverays when the marker M tracked by using the moving-object trackingapparatus 4 exists at a specific position (gating window) 41.

The medical image processing apparatus 3 and the moving-object trackingapparatus 4 of the present embodiment includes hardware resources suchas a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM(Random Access Memory), and a HDD (Hard Disc Drive), and is configuredas a computer in which information processing by software is achievedwith the use of the hardware resources by causing the CPU to executevarious programs.

Further, a medical image processing method of the present embodiment isachieved by causing the computer to execute the various programs.

In addition, the X-ray imaging apparatus 7 and the respirationmonitoring apparatus 8 are connected to the moving-object trackingapparatus 4. In each of the X-ray images 40, an image of the marker Mappears. Further, the moving-object tracking apparatus 4 tracks theposition of the marker M in each X-ray image 40 generated by imaging thepatient P with the use of the X-ray imaging apparatus 7 duringradiotherapy, and monitors the respiratory state (e.g., breathingwaveform) of the patient P by using the respiration monitoring apparatus8. Moreover, the moving-object tracking apparatus 4 specifies theirradiation timing of the radioactive rays R, and outputs an irradiationtiming signal.

The X-ray imaging apparatus 7 includes two X-ray irradiators 9configured to irradiate the patient P with X-rays and two X-raydetectors 10 configured to detect X-rays transmitted through the patientP. Incidentally, each of the X-ray detectors 10 is composed of, e.g., aflat panel detector (FPD) or an image intensifier.

In other words, the radiation therapy system 1 of the present embodimentis provided with two pairs of X-ray irradiation and detection units,each of which includes one X-ray irradiator 9 and one X-ray detector 10.The three-dimensional position of the marker M can be specified bysimultaneously performing X-ray imaging from two different directionswith the use of the two pairs of the X-ray irradiators 9 and the X-raydetectors 10. In addition, it is possible to associate the same markersM, which are depicted in the respective X-ray images 40 generated bysimultaneously imaging the patient P from the two directions, with eachother by performing image processing.

In actual X-ray imaging, two pairs of the X-ray irradiators 9 and theX-ray detectors 10 are used for imaging the patient P from twodirections (e.g., the direction from the right-hand side of the patientP and the direction the from left-hand side of the patient P) so as togenerate a pair of X-ray images (medical images) 40. Further, as to aDRR image (Digitally Reconstructed Radiograph image, digitalreconstructed radiograph, or medical image) 46 described below, a pairof images can be obtained. However, in the following description, theX-ray images 40 and the DRR images 46 taken from one direction will beexemplified in order to facilitate understanding of the embodiments(FIG. 5 to FIG. 8).

As shown in FIG. 5, the lesion area T and plural markers M appear in theX-ray image 40. It is determined by the conditions of the X-rayirradiators 9 and the X-ray detectors 10 such as their arrangement andtheir orientation how the lesion area T and each marker M are depictedin the X-ray image 40. Since the X-ray images 40 are time-sequentiallyand continuously generated, it is possible to generate a moving imagefrom the plural X-ray images (frames) 40. By performing image processingon the time-sequential X-ray images 40, it is possible to grasp themovement of the marker M, i.e., the motion of the lesion area T.

For instance, by connecting the position of the marker M of each of theplural X-ray images 40, it is possible to acquire the moving track 42 ofthe marker M. In the moving track 42 of the marker M, the end pointposition 43 at the time of exhaling (i.e., breathing out) and the endpoint position 44 at the time of inbreathing (i.e., inhaling) are clear.The endpoint position 43 at the time of exhaling is defined as thespecific position 41. When the marker M is present at this specificposition 41, the radioactive rays R are radiated onto the lesion area T.In this manner, it is possible to realize accurate respiratorysynchronized irradiation on the basis of tracking processing of themarker M. Incidentally, the specific position 41 is a specific area(e.g., rectangular area) included in the X-ray image 40 as shown in FIG.5.

When the entire range of the X-ray image 40 is to be processed on areal-time basis, the processing load of the CPU becomes high. Thus, inorder to reduce the load of the image processing, a specific range(search range) 45, where there is a possibility that the marker M isdepicted in the X-ray image 40, is set and image processing of searchingonly this specific range 45 is performed. In addition, it is possible tothree-dimensionally acquire the position of the marker M and its movingtrack 42 by acquiring a pair of images generated by imaging the patientP in two directions as the X-ray images 40 (DRR images 46) and thenspecifying the specific range 45 and the specific position 41 for thepair of the X-ray images 40 (DRR images 46).

As shown in FIG. 1, the respiration monitoring apparatus 8 is connectedto a respiration sensor 11 which is attached to the patient P. Thisrespiration sensor 11 is used for monitoring the respiratory state ofthe patient P. The respiration monitoring apparatus 8 outputsrespiratory information indicative of the respiratory state of thepatient P to the moving-object tracking apparatus 4. In the presentembodiment, the radiation therapy system 1 is configured to radiate theradioactive rays R onto the lesion area T when both of the followingfirst and second conditions are satisfied. The first condition is thatthe respiratory state of the patient P acquired by the respirationmonitoring apparatus 8 indicates that the patient P exhaled. The secondcondition is that the marker M exists at the specific position 41. Itshould be noted that the radioactive rays R may be radiated onto thelesion area T when the marker M exists at the specific position 41regardless of the respiratory state of the patient P.

In addition, the radiation irradiation apparatus 5 is connected to anirradiation controller 12. The irradiation timing of the radioactiverays R is controlled by the irradiation controller 12. Further, theirradiation controller 12 is connected to the moving-object trackingapparatus 4. The irradiation controller 12 controls the radiationirradiation apparatus 5 in such a manner that the radiation irradiationapparatus 5 radiates the radioactive rays R when the irradiationcontroller 12 receives the irradiation timing signal outputted from themoving-object tracking apparatus 4.

As shown in FIG. 2, the medical examination apparatus 2 is an apparatusfor performing computed tomography of the patient P, and includes aprojection data generator 13 configured to generate projection data ofthe patient P by imaging the patient P in plural directions and athree-dimensional volume image generator 14 configured to generate astereoscopic and three-dimensional volume image of the patient P on thebasis of plural two-dimensional projection data obtained by theprojection data generator 13. The three-dimensional volume imageincludes, e.g., information of plural voxels. The three-dimensionalvolume image generator 14 outputs the three-dimensional volume image tothe medical image processing apparatus 3. It is possible to generate astereoscopic moving image of the patient P by time-sequentially andconsecutively performing computed tomography. This makes it possible toacquire the three-dimensional movement of the lesion area T and themarker(s) M.

The medical image processing apparatus 3 includes a first inputinterface (i.e., first acquisition unit) 15, a three-dimensional volumeimage memory 16, a second input interface (i.e., second acquisitionunit) 17, a geometry information memory 18, and a positional informationanalyzer (i.e., positional information acquisition unit) 19. The firstinput interface 15 acquires a three-dimensional volume image of thepatient P from the medical examination apparatus 2. Thethree-dimensional volume image memory 16 stores the three-dimensionalvolume image acquired by first input interface 15. The second inputinterface 17 acquires geometry information of the X-ray irradiators 9and the X-ray detectors 10 in the X-ray imaging apparatus 7 used forimaging the patient P to generate the X-ray images 40. The geometryinformation memory 18 stores the geometry information acquired by thesecond input interface 17. The positional information analyzer 19acquires (i.e., calculates) positional information (e.g., coordinates)of the marker M on the basis of the three-dimensional volume imagestored in the three-dimensional volume image memory 16.

Incidentally, the geometry information includes parameters indicatingthe positions of the respective X-ray irradiators 9, the positions ofthe respective X-ray detectors 10, and the orientation of the X-raydetection plane of each X-ray detector 10. The geometry information ispreconfigured on the basis of, e.g., design drawing data (CAD data) ofthe X-ray imaging apparatus 7. Further, the second input interface 17may store the geometry information in advance in addition to acquiringthe geometry information from an external device. When the X-ray imagingapparatus 7 is movable, the second input interface 17 acquires andstores the geometry information in each state from the outside.

Moreover, the three-dimensional volume image of the patient P containsthe CT value of the metal (e.g., gold) constituting the marker M. Thepositional information analyzer 19 can acquire the three-dimensionalpositional information of the marker M placed in the body of the patientP by specifying the CT value of the metal. Incidentally, the medicalexamination apparatus 2 time-sequentially and consecutively performscomputed tomography. Accordingly, the respiratory state of the patient Pis also time-sequentially monitored so as to correspond to the timing ofeach imaging (i.e., in synchronization with each imaging). Therespiratory information indicative of the respiratory state is stored inthe three-dimensional volume image memory 16 in association with thethree-dimensional volume image obtained from the medical examinationapparatus 2.

In addition, the three-dimensional volume image of the patient Pincludes the positional information of the lesion area T. Although thepositional information of the lesion area T in the three-dimensionalvolume image is inputted by a user (e.g., a doctor) at the time oftreatment planning, the positional information of the lesion area T maybe automatically identified to assist the user. When the positionalinformation of the lesion area T at a specific time is inputted by auser, the positional information of the lesion area T and the marker Mat other times can be calculated by image registration and thus can beautomatically acquired. The positional information of the marker M inthe three-dimensional volume image can be automatically acquired fromthe CT value as described above.

The medical image processing apparatus 3 includes a DRR image generator20 configured to generate the DRR images 46 on the basis of thethree-dimensional volume image of the patient P and the geometryinformation of the X-ray imaging apparatus 7, and further includes a DRRimage monitor (i.e., reconstructed-image display unit) 21 configured todisplay each DRR image 46. It should be noted that each DRR image 46 isa virtual X-ray image 40 obtained by virtually imaging athree-dimensional volume image with the use of the X-ray imagingapparatus 7. Since the X-ray image 40 and the DRR image 46 are imageshaving almost the same composition, it is assumed in the followingdescription that each of the four schematic image diagrams exemplifiedin FIG. 5 to FIG. 8 is the X-ray image 40 and is also the DRR image 46.

As shown in FIG. 2, the medical image processing apparatus 3 includes aspecific-setting-information generator 22 and aspecific-setting-information memory 23. The specific-setting-informationgenerator 22 generates specific setting information on the basis of thethree-dimensional volume image of the patient P, the geometryinformation of the X-ray imaging apparatus 7, the positional informationof the marker M, and the DRR images 46. The specific setting informationis used for setting of imaging for generating an image depicting themarker M or setting of image processing of this image. Thespecific-setting-information memory 23 stores the specific settinginformation. An image depicting the marker M (i.e., an image in whichthe marker M appears) includes both of the X-ray images 40 generated bythe X-ray imaging apparatus 7 and the DRR images 46 generated by the DRRimage generator 20.

The specific setting information (tracking condition) of the presentembodiment relates to the setting used for generating the X-ray image 40with the X-ray imaging apparatus 7 and for tracking the movement of themarker M with the moving-object tracking apparatus 4. For instance, thespecific setting information includes information for predicting themoving track 42 of the marker M and setting the specific range 45 andthe specific position 41 in the X-ray images 40 (FIG. 5). In addition,the specific setting information further includes information as towhether one of the plural markers M provided in the patient P is set asa target of image processing or not.

By generating the specific setting information in this manner, it ispossible to automate the setting of the specific range 45 and thespecific position 41 used for the image processing to be performed bythe moving-object tracking apparatus 4. Thus, it is possible to savetime and labor for a user such as a doctor or a radiological technician.Further, by generating the specific setting information with the use ofthe positional information of the marker M, it is possible to image anarea including the marker M or perform image processing on an image inwhich the marker M is depicted depending on the position of the markerM.

It should be noted that the specific setting information can begenerated in advance of imaging the patient P (i.e., generating theX-ray image 40). As compared with a case where it is required to imagethe patient P in advance to generate the X-ray image 40 because settingas to tracking the marker M is manually performed, the setting as totracking the marker M can be completed in a shorter time in the presentembodiment. Since it is not required to preliminarily image the patientP in the present embodiment, exposure dose to the patient can bereduced.

Since image processing can be performed mainly on the specific range 45depicting the marker M by including the information for setting thespecific range 45 in the specific setting information, the processingload can be reduced. Further, since the specific setting informationincludes information for setting the specific position 41 (gatingwindow), it is possible to set a radiation irradiation timing of theradiation irradiation apparatus 5 by using the specific settinginformation. It should be noted that the specific position 41 may be apinpoint or an area having a predetermined margin.

The specific setting information may be used for setting for improvingthe output of X-rays radiated onto a range where there is a highpossibility that the marker M is present. By improving the irradiationoutput of X-rays to a range where there is a high possibility that themarker M is present as described above, the radiation therapy system 1can clearly image the marker M in the X-ray image 40 while reducing theexposure dose of tissues other than the marker M. Accordingly, it ispossible to more easily perform the image processing for specifying themarker M which is depicted in each X-ray image 40.

As shown in FIG. 4, there are parts which are hard to transmit X-rayssuch as a bone 47 and an internal organ 48 in the body of the patient Pand/or metal parts of the bed 6. When the image of the marker Msuperimposes the image 49 of such a part (FIG. 6), it is difficult tospecify the position of the marker M by image processing. For thisreason, it is preferable that the specific-setting-information generator22 generates the specific setting information used for specifying themarker M clearly depicted on the X-ray image 40 out of the pluralmarkers M placed in the body of the patient P.

For instance, three markers M1 to M3 are placed in the body. In thiscase, the specific-setting-information generator 22 identifies thestraight line L1 which extends from the X-ray irradiator 9 to the X-raydetector 10 so as to pass the position of the marker M1, the straightline L2 which extends from the X-ray irradiator 9 to the X-ray detector10 so as to pass the position of the marker M2, and the straight line L3which extends from the X-ray irradiator 9 to the X-ray detector 10 so asto pass the position of the marker M3.

Further, the specific-setting-information generator 22 virtually placesa three-dimensional volume image between the X-ray irradiator 9 and theX-ray detector 10. When the three-dimensional volume image is a CTimage, each voxel constituting the CT image is given a CT valueindicative of difficulty of transmitting X-rays. A larger CT value isgiven to each voxel of a portion which is difficult to transmit X-rayssuch as the bone 47 and the internal organ 48 as compared withrespective CT values of other voxels. For this reason, thespecific-setting-information generator 22 calculates the total value ofthe CT values of all the voxels that are passing points of the straightline L1 in the virtual three-dimensional volume image existing betweenthe X-ray irradiator 9 and the X-ray detector 10. The specific settingunit 22 calculates the total value of the CT values of all the voxelsthat are passing points of the straight line L2 in the virtualthree-dimensional volume image, and similarly calculates the total valueof the CT values of all the voxels that are passing points of thestraight line L3 in the virtual three-dimensional volume image. Thespecific-setting-information generator 22 selects a straight linecorresponding to the minimum total value of the three total values. Inthe case of FIG. 4, the straight line L1 is specified because it doesnot pass through the area of the internal organ 48 compared with thestraight lines L1 and L2. Then, the marker M1 corresponding to thespecified straight line L1 is set as a target of image processing. Inthis manner, the marker M1 suitable for the image processing can beselected from the plural markers M1 to M3.

When the three-dimensional volume image is a CT image, thespecific-setting-information generator 22 of the present inventionselects and sets the marker M1 as the target of image processing fromthe straight lines L1 to L3 passing through the respective positions ofthe markers M1 to M3. This is because the marker M1 corresponds to thestraight line L1 having the smallest sum of the CT values of all thevoxels existing on the straight line from the X-ray irradiator 9 to theX-ray detector 10. In this manner, when the patient P is imaged togenerate the X-ray images 40, the marker M1 most clearly depicted in theX-ray images 40 can be selected from the plural markers M1 to M3. Itshould be noted that any one of the markers M1 to M3 may be subjected tothe image processing. Additionally, two or more of the markers M1 to M3may be subjected to the image processing. When two or more markers areset as the targets of the image processing, two straight lines may bespecified in ascending order of the total value of the voxel values sothat the specified two markers are targeted.

The marker M as the image processing target may be specified on thebasis of the voxel values of the three-dimensional volume image asdescribed above or may be specified on the basis of the evaluation ofthe contrast of each DRR image 46. Further, the marker M as the imageprocessing target may be specified by using the evaluation of the voxelvalues of the three-dimensional volume image and the evaluation of thecontrast of the DRR image 46 in combination.

When the specific-setting-information generator 22 evaluates thecontrast of the DRR image 46, the specific-setting-information generator22 specifies (i.e., selects) the one having the highest contrast withthe surroundings from the respective images of the markers M1 to M3depicted in the DRR image 46. Since it is only necessary to evaluate thecontrast with the surroundings, it is not necessary to generate theentire DRR image 46. If only the partial images around the markers M1 toM3 are generated, the contrast with the surroundings can be calculated.

Further, the specific setting information may include information forchanging the specific range 45 according to the respiratory state of thepatient P, which is acquired by using the respiration monitoringapparatus 8 for monitoring respiration of the patient P. For instance,when the patient P expands the volume of the lung by lowering thediaphragm and inhales, the marker M moves to the lower side of the X-rayimage 40 as shown in FIG. 7. When the patient P narrows the volume ofthe lung by raising the diaphragm and exhales, the marker M moves to theupper side of the X-ray image 40. In this case, the specific range 45may be changed in such a manner that only the upper side of the movingtrack 42 of the marker M is defined as the specific range 45 a from theposterior half period of exhaling to the anterior half period ofinhaling while only the lower side of the moving track 42 of the markerM is defined as the specific range 45 b from the posterior half periodof inhaling to the anterior half period of exhaling.

In this manner, the specific ranges 45 a and 45 b are set according tothe respiratory state of the patient P, and it is possible toappropriately image the patient P for generating the X-ray images 40, ineach of which the marker M is satisfactorily clearly depicted. Inaddition, since it is possible to set the specific ranges 45 a and 45 bof the minimum necessary area, load of the image processing can bereduced by narrowing the specific ranges 45 a and 45 b. Further, byusing the specific ranges 45 a and 45 b in accordance with therespiration information outputted from the respiration monitoringapparatus 8, the risk of erroneously tracking noise as the marker M ismore reduced. Although a description has been given of the case wheretwo specific ranges are set depending on the respiratory state of thepatient P, three or more specific ranges may be set. When three or morespecific ranges are set, the load of tracking image processing can befurther reduced.

Further, the plural markers M1 to M3 may be tracked in a complex mannerby using the X-ray images 40. For instance, as shown in FIG. 8, a partof each of the moving tracks 42 of the plural markers M1 to M3 may behidden in the image 49 of, e.g., the bone 47. In such a case, only theupper side of the moving track 42 of the predetermined marker M1 isdefined as the specific range 45 c from the posterior half period ofexhaling to the anterior half period of inhaling and only the lower sideof the moving track 42 of the other marker M2 is defined as the specificrange 45 d from the posterior half period of inhaling to the anteriorhalf period of exhaling. The end point position 43 of the marker M2 atthe time of exhaling is defined as a specific position 41 a. In thismanner, it is possible to track any marker M at any point in thebreathing cycle.

A user such as a doctor or radiological technician can change thespecific setting information while referring to the DRR images 46 or theX-ray images 40 of the patient P imaged by using the X-ray imagingapparatus 7 during rehearsal before treatment. For instance, a user canselect the marker M to be tracked, change the specific ranges 45 c and45 d, or change the specific position 41 a in the moving-object trackingapparatus 4.

As shown in FIG. 2, the medical image processing apparatus 3 includes aselection input interface (i.e., selection-input reception unit) 24, amarker setter (i.e., marker setting unit) 25, a range input interface(i.e., range-input reception unit) 26, a range changer (i.e., rangechanging unit) 27, a rehearsal-image input interface (i.e.,fluoroscopic-image acquisition unit) 28, and a rehearsal-image monitor(i.e., fluoroscopic-image display unit) 29. The selection inputinterface 24 receives a selection instruction of the marker M to beinputted by a user. The marker setter 25 sets the marker M, which isselected by the selection instruction, as a tracking target. The rangeinput interface 26 receives a change instruction of the specific range45 or the specific position 41 to be inputted by a user. The rangechanger 27 changes the specific setting information on the basis of thespecific range 45 or the specific position 41 which corresponds to thechange instruction. The rehearsal-image input interface 28 acquires theX-ray images 40 of the patient P imaged by using the X-ray imagingapparatus 7 (the moving-object tracking apparatus 4) during rehearsalbefore treatment. The rehearsal-image monitor 29 displays each X-rayimage 40.

The above-described DRR image monitor 21 and the rehearsal-image monitor29 may be configured as an integral monitor which switches betweendisplay of the DRR image 46 and display of the X-ray image 40 ordisplays both of the DRR image 46 and the X-ray image 40 in parallel(i.e., side by side in the vertical or horizontal direction). Further,each of the DRR image monitor 21 and the rehearsal-image monitor 29 maybe configured as a separate monitor.

Further, the DRR image monitor 21 or the rehearsal-image monitor 29 setsthe specific range 45 in the DRR image 46 or the X-ray image 40 on thebasis of the specific setting information stored in thespecific-setting-information memory 23. When displaying the DRR image 46or the X-ray image 40, the DRR image monitor 21 or the rehearsal-imagemonitor 29 displays a range indication 52 indicative of the specificrange 45 in such a manner that the range indication 52 is superimposedon the image (FIG. 5 to FIG. 8).

For instance, the range indication 52 is displayed so as to surround themoving track 42 of the marker M in the image. In this manner, a user cangrasp the range, in which the marker M appears in the DRR image 46 orthe X-ray image 40, by the range indication 52. Further, the medicalimage processing apparatus 3 may be configured to output or display therange indication 52 which is sufficient for a user to sufficientlyunderstand related information such as the specific ranges 45 a, 45 b,45 c, and 45 d.

Then, the selection input interface 24 receives an instruction to selectthe marker M inputted by the user. In addition, the marker setter 25sends the received selection instruction to thespecific-setting-information generator 22 such that the selectioninstruction is reflected on generation of the specific settinginformation. Further, the range input interface 26 receives a changeinstruction to change the specific range 45 or the specific position 41inputted by the user. Moreover, the range changer 27 changes thespecific setting information stored in the specific-setting-informationmemory 23 on the basis of the received change instruction. Incidentally,the selection input interface 24 and the range input interface 26include a user interface (input unit) that can be operated by a user,such as a keyboard, a mouse, and a touch panel. The range inputinterface 26 does not need to receive a modification instruction from auser. For instance, the range input interface 26 may be an interface towhich a modification instruction is inputted by an external program fordetermining whether the specific range 45 is correct or not.

Further, the marker setter 25 may automatically select the appropriatemarker M from the plural markers M on the basis of the DRR image 46generated by the DRR image generator 20. For instance, the marker Mlocated closest to the lesion area T may be selected, or the marker Mhaving a high contrast with the surroundings may be selected. Here, themarker setter 25 may select the appropriate marker M on the basis of thespecific setting information stored in the specific-setting-informationmemory 23, or may newly select the appropriate marker M so as to sendthe information of the selected marker M to thespecific-setting-information generator 22.

The medical image processing apparatus 3 may be configured such that auser can change the marker M automatically selected by the marker setter25. For instance, when there are plural markers M, the marker setter 25may surround the markers M as choices with the respective rangeindications 52 (FIG. 6) and select the range indication 52, which theuser determined to be appropriate, from these range indications 52.

In this manner, the specific range 45 in which the marker M appears canbe appropriately modified according to a user's decision. Further, whilea user is watching the actual X-ray images 40 generated by imaging thepatient P using the X-ray imaging apparatus 7 during rehearsal, the usercan select the marker M, which is suitable for imaging the patient P togenerate the X-ray image 40 or suitable for the image processing of theX-ray image 40, from the plural markers M.

As shown in FIG. 3, the moving-object tracking apparatus 4 of the firstembodiment includes a specific-setting-information input interface(i.e., specific-setting-information acquisition unit) 30, an X-ray imageinput interface (i.e., X-ray image acquisition unit) 31, a range setter(i.e., range setting unit) 32, and an X-ray image monitor (i.e., X-rayimage display unit) 33. The specific-setting-information input interface30 acquires the specific setting information from the medical imageprocessing apparatus 3. The X-ray image input interface 31 acquires theX-ray images 40 generated by imaging the patient P with the use of theX-ray imaging apparatus 7. The range setter 32 sets the specific range45 indicative of the range in which the marker M is depicted in theX-ray images 40, on the basis of the specific-setting-information. TheX-ray image monitor displays the X-ray images 40.

Here, the specific setting information acquired by thespecific-setting-information input interface 30 is inputted to the X-rayimaging apparatus 7. The X-ray imaging apparatus 7 uses the specificsetting information for imaging the patient P so as to generate theX-ray image 40 in which the marker M appears. For instance, the X-rayimaging apparatus 7 sets the arrangement of the X-ray irradiators 9 andthe X-ray detectors 10 on the basis of the specific setting information.In accordance with this setting, the X-ray irradiators 9 and the X-raydetectors 10 operate, and then X-ray imaging during rehearsal and X-rayimaging at the time of treatment are performed. Further, on the basis ofthe specific setting information, the X-ray imaging apparatus 7 mayincrease output of X-rays radiated onto the range where there is a highpossibility that the marker M exists. Additionally or alternatively, theX-ray imaging apparatus 7 may reduce output of X-rays radiated onto therange where there is a high possibility that the marker M does notexist.

Note that the X-ray image 40 generated by the X-ray imaging apparatus 7at the time of rehearsal before treatment is outputted to the medicalimage processing apparatus 3. In addition, each X-ray image 40 generatedby the X-ray imaging apparatus 7 during treatment is displayed on theX-ray image monitor 33. When displaying the X-ray image 40, the X-rayimage monitor 33 superimposes the range indication 52 indicative of thespecific range 45 on the X-ray image 40 (FIG. 5 to FIG. 8).

Further, the moving-object tracking apparatus 4 includes a trackingprocessor (i.e., tracking unit) 35, an irradiation determinationprocessor (i.e., irradiation determination unit) 36, and anirradiation-signal output interface (i.e., irradiation-signal outputunit) 37. The tracking processor 35 performs image processing oftracking the position of the marker M appearing in the X-ray images 40by using the specific setting information. The irradiation determinationprocessor 36 determines whether it is the irradiation timing ofradioactive rays R or not, on the basis of the position of the marker M.The irradiation-signal output interface 37 outputs the irradiationtiming signal when it is determined to be the irradiation timing by theirradiation determination processor 36.

Here, the moving-object tracking apparatus 4 tracks the marker Mappearing in the X-ray images 40 by using the tracking processor 35.When the marker M exists at the specific position 41, i.e., when theirradiation determination processor 36 determines that it is theirradiation timing of the radioactive rays R, the irradiation-signaloutput interface 37 outputs the irradiation timing signal to theirradiation controller 12. When receiving the irradiation timing signaloutputted from the moving-object tracking apparatus 4, the irradiationcontroller 12 causes the radiation irradiation apparatus 5 to radiateradioactive rays R.

The moving-object tracking apparatus 4 further includes an evaluator(i.e., evaluation unit) 38 and a warning output interface (i.e., warningoutput unit) 39. The evaluator 38 evaluates magnitude relationshipbetween a predetermined threshold value and a gray value of eachpixel/voxel of the area of the marker M positionally detected in theX-ray image 40. The warning output interface 39 outputs a warning signalwhen there is a possibility that the detection of the marker M using thetracking processor 35 has failed.

The tracking processor 35 detects the marker M by performing imageprocessing of the specific range 45 of the X-ray images 40. Varioustechniques can be applied to this image processing. In a part of thisimage processing, the tracking processor 35 performs processing ofdetecting the marker M appearing in the X-ray images 40 on the basis ofthe gray value of each pixel in the specific range 45 in the presentembodiment. For instance, when there is a circular image in the specificrange 45 and the circular image is darker than the surroundings, it isestimated that the spherical marker M is depicted as a circular image.

In the present embodiment, it is assumed that each portion which is hardto transmit X-rays is darkly depicted on the X-ray images 40, such asthe marker M. Further, in each X-ray image, a gray value of a pixel of abright part is large and a gray value of a pixel of a dark part issmall. In addition, the X-ray image 40 can be reversed in black andwhite. In the case of reversing black and white from the above-describedpixel-value aspect, a portion which is hard to transmit X-rays appearsrelatively bright on each X-ray image 40. Thus, the terms “bright” and“dark” and magnitude of a gray value described in the followingdescription can be arbitrarily changed according to the black and whitereversal of the X-ray image 40.

Since various portions such as the internal organs of the patient P aredepicted in the X-ray image 40, the marker M may be erroneously detectedin some cases. When radiation irradiation is performed in such a statethat a tracking failure occurs, there is a possibility that radiationirradiation cannot be performed on an appropriate position of thepatient P.

Thus, the evaluator 38 of the present embodiment evaluates the grayvalue of each pixel in the specific range 45 on the basis of a presetthreshold value. Since the marker M is harder to transmit X-rays thanbody tissues, in the entire X-ray image, the gray value of the imageportion of the marker M is significantly different from the imageportion of the surrounding living tissues or an image portion generatedby noise. Accordingly, for instance, the threshold value is previouslyset to a value which is indicative of being relatively bright amongpossible gray values used for each pixel of the marker M. Then, theevaluator 38 evaluates whether the gray value of the position detectedas the marker M in the X-ray image 40 is larger or smaller than thethreshold value. When the evaluated gray value is larger than thethreshold value, the evaluated gray value is too bright for the marker Mand there is a high possibility that the tracking processor 35 haserroneously detected, as the marker M, the position where the marker Mis not depicted.

Further, depending on the magnitude relation evaluated by the evaluator38, the warning output interface 39 outputs the warning signal to theirradiation controller 12. The warning signal may be outputted only whenthe gray value of the detection position is larger than the thresholdvalue. In addition, the moving-object tracking apparatus 4 may performnotification of warning by display or voice together with output of thewarning signal. By performing notification of warning, a user noticesthe risk and can quickly interrupt the treatment. Further, a history ofwarnings may be stored.

In this manner, when there is a possibility that detection of the markerM has failed, i.e., when there is a possibility that radiationirradiation cannot be performed on an appropriate position of thepatient P, the warning can be outputted. When the irradiation controller12 receives the warning signal regardless of receiving theabove-described irradiation timing signal, the irradiation controller 12controls the radiation irradiation apparatus 5 such that irradiation ofradioactive rays R is not performed.

In other words, the moving-object tracking apparatus 4 of the presentinvention includes (a) the range setter 32 for setting the specificrange 45 indicative of the range in which the marker M appears in theX-ray images 40 by using the specific setting information and (b) theevaluator 38 for evaluating the magnitude relationship of the gray valueof the position detected as the marker M with respect to thepredetermined threshold value, and the warning output interface 39outputs the warning signal when the gray value of the detection positionis larger than the threshold value. In this manner, it is possible toquantitatively evaluate the presence/absence of the possibility that thedetection of the marker M has failed, on the basis of the predeterminedthreshold value.

Although the warning signal is outputted to the irradiation controller12 in the present embodiment, it is not necessarily required to outputthe warning signal to the outside of the moving-object trackingapparatus 4. For instance, the warning signal may be inputted to theirradiation-signal output interface 37. The moving-object trackingapparatus 4 may be configured such that the irradiation timing signal isnot outputted from the irradiation-signal output interface 37 in thecase of outputting the warning signal.

The radiation irradiation apparatus 5 of the present embodiment radiatesradioactive rays R onto the lesion area T when the marker M tracked bythe moving-object tracking apparatus 4 exists at the specific position41. By tracking the marker M in this manner, it is possible to grasp themovement of the lesion area T and radiate the radioactive rays R whenthe lesion area T is at an appropriate position.

Next, a description will be given of the specific-setting-informationgeneration processing (medical image processing method) executed by themedical image processing apparatus 3 with reference to FIG. 9 and FIG.10. Although the image processing described below includes processing ofmoving images, processing of still images will be exemplified below inorder to facilitate understanding of the specific-setting-informationgeneration processing.

First, in the case of preparing a treatment plan, a three-dimensionalvolume image of the patient P is generated by examining (i.e., imaging)the patient P in which the marker M is placed with the use of themedical examination apparatus 2.

In the step S11 (i.e., the first acquisition step), the first inputinterface 15 of the medical image processing apparatus 3 acquires thethree-dimensional volume image from the medical examination apparatus 2.

In the next step S12 (i.e., the second acquisition step), the secondinput interface 17 acquires the geometry information of the X-rayirradiators 9 and the X-ray detectors 10 in the X-ray imaging apparatus7.

In the next step S13, the positional information analyzer 19 acquiresthree-dimensional positional information of the marker M placed in thebody of the patient P on the basis of the value of each voxelconstituting the three-dimensional volume image.

In the next step S14, the DRR image generator 20 generates the DRR image46 on the basis of the three-dimensional volume image of the patient Pand the geometry information of the X-ray imaging apparatus 7.

In the next step S15, the specific-setting-information generator 22evaluates the value of each voxel constituting the three-dimensionalvolume image and/or the contrast of the image portion of the marker Mdepicted in the DRR image 46.

In the next step S16, depending on the evaluation result, thespecific-setting-information generator 22 selects the marker expected tobe depicted with the highest contrast in the X-ray image 40 from amongthe markers M1 to M3, as the target of image processing performed by themoving-object tracking apparatus 4.

In the next step S17, the specific-setting-information generator 22performs setting of the specific range 45 (FIG. 5) of each of the X-rayimages 40 and the DRR image 46.

In the next step S18, the specific-setting-information generator 22changes the setting of the specific range 45 when the specific range 45is changed depending on respiration of the patient P (FIG. 7 and FIG.8).

In the next step S19, the specific-setting-information generator 22performs setting of the specific position 41 of each of the X-ray images40 and the DRR image 46.

In the next step S20 (i.e., the specific-setting-information generationstep), the specific-setting-information generator 22 generates thespecific setting information which includes various settings.

In the next step S21, the DRR image monitor 21 displays the DRR image 46and the range indication 52 of the specific range 45. When there areplural choices for the marker M to be tracked, the range indications 52corresponding to the respective markers M are displayed.

In the next step S22, the selection input interface 24 receives theselection instruction of the marker M inputted by a user at the time oftreatment planning.

In the next step S23, the range input interface 26 receives the changeinstruction to change the specific range 45 or the specific position 41inputted by a user.

In the next step S24, the marker setter 25 sends the received changeinstruction to the specific-setting-information generator 22 so as toreflect the change instruction in generation of the specific settinginformation, and the range changer 27 changes the specific settinginformation stored in the specific-setting-information memory 23 on thebasis of the received change instruction.

In the next step S25, the rehearsal-image input interface 28 acquiresthe X-ray image 40 of the patient P generated by using the X-ray imagingapparatus 7 (the moving-object tracking apparatus 4) during rehearsalbefore treatment.

In the next step S26, the rehearsal-image monitor 29 displays the X-rayimage 40 and the range indication 52 of the specific range 45. Whenthere are plural choices for the marker M to be tracked, the rangeindications 52 corresponding to the respective markers M are displayed.

In the next step S27, the selection input interface 24 receives theselection instruction to select the marker M to be inputted by a userduring rehearsal before treatment.

In the next step S28, the range input interface 26 receives the changeinstruction to change the specific range 45 or the specific position 41to be inputted by a user.

In the next step S29, the marker setter 25 sends the received selectioninstruction to the specific-setting-information generator 22 so as toreflect the received selection instruction in generation of the specificsetting information, and the range changer 27 changes the specificsetting information stored in the specific-setting-information memory 23on the basis of the received change instruction.

In the next step S30, the medical image processing apparatus 3 outputsthe generated specific setting information to the moving-object trackingapparatus 4. As to the output of the specific setting information, thespecific setting information may be outputted to the moving-objecttracking apparatus 4 via a network or may be outputted to themoving-object tracking apparatus 4 after outputting the specific settinginformation to a storage medium. It is possible that the medical imageprocessing apparatus 3 and the moving-object tracking apparatus 4 areintegrally configured as one personal computer. Afterward, the medicalimage processing apparatus 3 completes the specific-setting-informationgeneration processing.

Next, a description will be given of the marker tracking processing(medical image processing method) executed by the moving-object trackingapparatus 4 with reference to FIG. 11 and FIG. 12.

First, in the step S31, the specific-setting-information input interface30 of the moving-object tracking apparatus 4 acquires the specificsetting information from the medical image processing apparatus 3.

In the next step S32, radiotherapy is started. Specifically, the X-rayimaging apparatus 7 images the patient P so as to generate the X-rayimages 40 of the patient P, and then the X-ray image input interface 31acquires the X-ray images 40 from the X-ray imaging apparatus 7.

In the next step S33, the tracking processor 35 and the range setter 32acquire respiratory information corresponding to the imaging time ofeach of the X-ray images 40 of the patient P from the respirationmonitoring apparatus 8.

In the next step S34, the range setter 32 sets the specific range 45 inthe X-ray images 40 on the basis of the specific setting information.When the specific range 45 is changed depending on or in response to therespiration of the patient P (FIG. 7 and FIG. 8), the range setter 32sets the specific range 45 corresponding to the respiration of thepatient P on the basis of the respiratory information inputted from therespiration monitoring apparatus 8.

In the next step S35, the X-ray image monitor 33 displays the X-rayimage 40 and the range indication 52 of the specific range 45.

In the next step S36, the tracking processor 35 detects the position ofthe marker M from the specific range 45 in the X-ray image 40.

In the next step S37, the evaluator 38 starts the process of evaluatingthe magnitude relationship between the threshold value and the grayvalue of the position where the marker M is detected. In other words,the evaluator 38 starts the process of detecting the gray value of eachpixel in the specific range 45.

In the next step S38, the evaluator 38 determines whether the gray valueof the position where the marker M is detected is larger than thethreshold value or not. When the gray value of the position where themarker M is detected is larger than the threshold value (i.e., when theposition where the marker M is detected is bright), the processingproceeds to the step S39 in which the warning output interface 39outputs the warning signal to the irradiation controller 12, and thenthe processing proceeds to the step S40. Conversely, when the gray valueof the position where the marker M is detected is smaller than thethreshold value (i.e., when the position where the marker M is detectedis dark), the warning signal is not outputted and the processingproceeds to the step S40.

In the step S40, the irradiation determination processor 36 determineswhether the position where the marker M is detected is included in thespecific position 41 or not (FIG. 5). When the position where the markerM is detected is included in the specific position 41, the processingproceeds to the step S41 in which the irradiation-signal outputinterface 37 outputs the irradiation timing signal to the irradiationcontroller 12 and then the processing proceeds to the step S42.Conversely, when the position where the marker M is detected is notincluded in the specific position 41, the irradiation timing signal isnot outputted and the processing proceeds to the step S42.

In the step S42, when the irradiation timing signal is inputted and thewarning signal is not inputted, the irradiation controller 12 controlsrespective components in such a manner that the radioactive rays R areradiated by using the radiation irradiation apparatus 5. Otherwise, theirradiation controller 12 controls respective components in such amanner that irradiation of the radioactive rays R is not performed.Thereafter, the processing proceeds to the step S43.

In the step S43, the moving-object tracking apparatus 4 determineswhether the radiotherapy has completed or not. The termination conditionof the radiotherapy is determined in the treatment plan in advance. Whenthe radiotherapy has not been completed, the processing returns to thestep S32 as described above. Conversely, when the radiotherapy iscompleted, the marker tracking process is completed.

In the present invention, setting of imaging a patient for generating animage in which the marker is depicted or setting of image processing ofthis image includes setting of fluoroscopic imaging for generatingfluoroscopic images, setting of generation of a digital reconstructedradiograph (setting of imaging in a virtual space), setting of imageprocessing of fluoroscopic images, and setting of image processing ofthe digital reconstructed radiographs.

Second Embodiment

Hereinbelow, a description will be given of the moving-object trackingapparatus (medical image processing apparatus) of the second embodimentby referring to FIG. 13 to FIG. 15. The same reference signs areassigned to the same components as the above-described embodiment ineach figure, and duplicate description is omitted. It should be notedthat the moving-object tracking apparatus and the medical imageprocessing apparatus are integrally configured in the second embodiment.

As shown in FIG. 13, the moving-object tracking apparatus 4A of thesecond embodiment includes a specific-setting-information generator 53configured to generate the specific setting information and an interlockdevice 54. In the second embodiment, the term “interlock” means tospecify a normal state and prohibit radiation irradiation in any otherstate (i.e., in an abnormal state). In the second embodiment, imagingfor generating the X-ray image 40 (FIG. 5) and tracking of the marker Mare performed on the basis of the specific setting information which isgenerated by the specific setting information generator 53.Additionally, the other configuration is almost the same as that of themoving-object tracking apparatus 4 (FIG. 3) of the first embodiment.Although the evaluator 38 and the warning output interface 39 areomitted for illustration in FIG. 13, these components may be provided inthe second embodiment. Further, the configuration of thespecific-setting-information generator 53 in the second embodiment mayhave the same configuration as that of the medical image processingapparatus 3 in the first embodiment.

The interlock device 54 of the moving-object tracking apparatus 4Aaccording to the second embodiment is a safety device for preventing theradiation irradiation apparatus 5 from radiating the radioactive rays Rwhen the state is not the normal state.

For instance, the timing suitable for irradiation is assumed to be thetiming when the patient P completely exhales (i.e., breathes out). Whenthe state of the patient P is not normal at the timing of breathing out,the patient P is in an abnormal state (e.g., a state that is not normal,such as coughing or sneezing) or it is in an abnormal state in whichtracking of the marker M has failed. If radiation irradiation isperformed in such an abnormal state, there is a possibility that theradioactive rays R hit a position deviated from the lesion area T.

For this reason, the interlock device 54 determines whether it is in thenormal state or not, by using the X-ray images 40. When it is determinedto be in the normal state, radiation irradiation is not prohibited. Whenit is determined to be in an abnormal state (i.e., in any stateexcluding the normal state), control for prohibiting radiationirradiation is performed. For the determination, the interlock device 54may use the entirety of at least one X-ray image 40 or other informationsuch as a partial image of the specific position 41 (FIG. 5), a partialimage in the vicinity the specific position 41, a partial image in thevicinity of the lesion area T.

The interlock device 54 includes a first-image input interface (i.e.,first image acquisition unit) 55, an motion-information input interface(i.e., motion-information acquisition unit) 56, a specifying processor(i.e., specification unit) 57, a feature calculator (i.e., featureacquisition unit) 58, a normal range memory (i.e., normal range storageunit) 59, a second-image input interface (i.e., second image acquisitionunit) 60, an image determination processor (i.e., image determinationunit) 61, and a determination-signal output interface (i.e.,determination-signal output unit) 62.

The first-image input interface 55 acquires first images which are theX-ray images (fluoroscopic images) 40 of the patient (object) P imagedduring rehearsal before treatment.

The motion-information input interface 56 acquires the respiratoryinformation (motion information) of the patient P which is acquired byusing the respiration monitoring apparatus 8 during rehearsal.

The specifying processor 57 specifies a timing suitable for radiationirradiation on the basis of the respiratory information, and acquiresthe first image which is generated by imaging the patient P at thisspecified timing.

The feature calculator 58 acquires feature of the first image acquiredby the specifying processor 57, and calculates a normal range which is arange of feature indicative of the normal state.

The normal range memory 59 stores parameters indicative of thecalculated normal range.

The second-image input interface 60 acquires second images which are theX-ray images 40 of the patient P imaged at times different from theimaging times of the respective first images (e.g., duringradiotherapy).

The image determination processor 61 acquires the feature from thesecond images, and determines whether the feature is included in thenormal range or not, by using the normal range indicated by theparameters being read out from the normal range memory 59.

The determination-signal output interface 62 outputs a determinationsignal indicating whether it is in the normal state or not, according tothe result of the determination.

The parameters representing the normal range are, for instance,parameters of a discriminator. As a discriminator, for instance, aone-class support vector machine, a two-class support vector machine, aneural network, a deep neural network, and decision tree can be used.Another discriminator may be used. The above-described determination isperformed by a discriminator. The parameters of the discriminator can belearned by machine learning with the use of the feature indicative ofthe normal state.

Since plural X-ray images 40 (first images) are generated bytime-sequentially and consecutively imaging the patient P duringrehearsal, it is possible to generate a moving image by using theseplural X-ray images 40. In addition, the respiratory information (motioninformation) acquired by the motion-information input interface 56 isinformation correlated with the movement of the lesion area T (i.e.,target part of irradiation). Further, the respiratory information isacquired in association with the imaging time of each of the X-rayimages 40.

In the present embodiment, the radioactive rays R are radiated when allof the following first to third conditions are satisfied. The firstcondition is that the respiratory state of the patient P acquired by therespiration monitoring apparatus 8 indicates the timing of breathing out(i.e., completely exhaling). The second condition is that theabove-described marker M exists at the specific position 41. The thirdcondition is that the image determination processor 61 of the interlockdevice 54 determines that the X-ray image 40 is in the normal state.

In addition, the feature calculator 58 of the interlock device 54acquires the feature of the X-ray images 40 (first images) generated byimaging the patient P during rehearsal before treatment. As the feature,for instance, a vector in which pixel values are arranged is used. TheX-ray images 40 used for learning are, e.g., respective imagescorresponding to several breaths. Since the state in which the patient Pis not coughing or sneezing is defined as the normal state, images whenthe patient P is not coughing or sneezing is selected from these imagesand used for the learning. An image in the normal state is called anormal image (specific image). Further, the X-ray images 40 may beimages generated by imaging the patient P in one direction or pluraldirections. The feature may be a vector in which the pixel values of theX-ray images 40 (first images) imaged in plural directions are arranged.The selection of images may be performed by a user or may beautomatically performed by the interlock device 54 depending on therespiratory information.

In the case of changing the definition of the normal state, the normalimage used for learning is also changed. For instance, in the case ofdefining the state where the marker M appears at the specific position41 as the normal state, the X-ray images 40 (first images) in this statemay be set as normal images to be used for learning. In this definitionof the normal state, the motion-information input interface 56 is notrequired in the interlock device 54. The normal range is, e.g., ahypersphere which encompasses the feature in the normal state in featurespace. The larger the size of the hypersphere is, the lower thedetection sensitivity of the abnormal state becomes. One-class supportvector machine is known as an optimization method for making the radiusof the hypersphere as small as possible under the condition that all thevectors which are the feature in the normal state are included. It ispossible to automatically set a hypersphere by using this one-classsupport vector machine. The dimension of the vectors may be compressedby principal component analysis. Among the X-ray images 40 (firstimages), any image indicating an abnormal state may be set as anabnormal image (i.e., non-specific image), and the discriminator mayperform learning under arbitrary supervised learning from the normalimages and abnormal images. As the discriminator of supervised learning,for instance, a two-class support vector machine, a neural network, adeep neural network, and a decision tree can be used.

The interlock device 54 determines whether it is in the normal state ornot, from the X-ray images 40 (second images) generated by imaging thepatient P during radiotherapy. Specifically, the interlock device 54acquires the feature from the X-ray images 40 (second images), anddetermines whether the acquired feature is included in the normal rangeor not, by using the discriminator which is indicated by the parametersbeing read out from the normal range memory 59.

The moving-object tracking apparatus 4A (interlock device 54) includesartificial intelligence based on machine learning. The normal range maybe set as the combined range including both of (a) the normal rangebeing set from only the normal image and (b) the normal range being setfrom a pair of the normal image and the abnormal image.

Next, a description will be given of the interlock processing (medicalimage processing method) to be performed by the moving-object trackingapparatus 4A of the second embodiment with reference to FIG. 14 and FIG.15. This interlocking processing is executed in parallel with the markertracking processing (FIG. 11 and FIG. 12) of the first embodiment.

First, in the step S51, rehearsal of X-ray imaging of the patient P isstarted by using the X-ray imaging apparatus 7 of the moving-objecttracking apparatus 4A.

In the next step S52 (i.e., first-image acquisition step), thefirst-image input interface 55 acquires the first images which are theX-ray images 40.

In the next step S53 (i.e., motion-information acquisition step), themotion-information input interface 56 acquires the respiratoryinformation (motion information) of the patient P.

In the next step S54 (i.e., specifying step), on the basis of therespiratory information, the specifying processor 57 specifies thetiming which is suitable for radiation irradiation and is the imagingtiming (time) of one of the first images.

In the next step S55, the specifying processor 57 determines the normalimage (specific image) on the basis of the image of the specificposition 41 (FIG. 5) included in the first image imaged at the specifiedtiming.

In the next step S56 (i.e., feature acquisition step), the featurecalculator 58 acquires the feature of the normal image and calculatesthe parameters indicative of the normal range which is the range of thefeature indicative of the normal state.

In the next step S57, the normal range memory 59 stores the parametersindicative of the calculated normal range, and thereby the rehearsal iscompleted.

In the next step S58, radiotherapy using the radiation irradiationapparatus 5 is started.

In the next step S59 (i.e., second-image acquisition step), thesecond-image input interface 60 acquires the second images which are theX-ray images 40.

In the next step S60, the image determination processor 61 performsdetermination on the second images on the basis of the normal rangewhich is represented by the parameters stored in the normal range memory59.

In the next step S61 (i.e., image determination step), as a continuationof this determination, the feature is acquired from the second imagesand it is determined whether or not the acquired feature is included inthe normal range represented by the parameters being read out from thenormal range memory 59.

When the feature of the second images is included in the normal range(i.e., when it is determined to be normal in the step S61), theprocessing proceeds to the step S62 (i.e., signal output step) in whichthe determination-signal output interface 62 outputs the irradiationnon-prohibition signal (i.e., determination signal) to the irradiationcontroller 12.

Conversely, when the feature of the second images is not included in thenormal range (i.e., when it is determined that the feature is not normalin the step S61), the processing proceeds to the step S63 (i.e., signaloutput step) in which the determination-signal output interface 62outputs the irradiation prohibition signal (i.e., determination signal)to the irradiation controller 12.

The irradiation controller 12 radiates the radioactive rays R by usingthe radiation irradiation apparatus 5 on condition that both theirradiation timing signal and the irradiation non-prohibition signal areinputted. Further, even when the irradiation timing signal is inputted,the irradiation controller 12 controls respective components such thatirradiation of the radioactive rays R using the radiation irradiationapparatus 5 is not performed in the case of receiving the irradiationprohibition signal.

In the next step S64, the moving-object tracking apparatus 4A determineswhether the radiotherapy has completed or not. When the radiotherapy hasnot been completed, the processing returns to the above-described stepS59. On the other hand, when the radiotherapy has been completed, theinterlocking processing is terminated.

In the second embodiment, a description has been given of the case wherethe irradiation prohibition signal and the irradiation non-prohibitionsignal are outputted to the irradiation controller 12 as one aspect.However, it is not necessary to output the irradiation prohibitionsignal and the non-irradiation prohibition signal to the outside of themoving-object tracking apparatus 4A. For instance, the irradiationprohibition signal and the irradiation non-prohibition signal may beinputted to the irradiation-signal output interface 37. Theirradiation-signal output interface 37 may be configured to output theirradiation timing signal when receiving the irradiation non-prohibitionsignal (i.e., when there is not input of the irradiation prohibitionsignal) and to stop output of the irradiation timing signal whenreceiving the irradiation prohibition signal (i.e., when there is notinput of the irradiation non-prohibition signal). When configuration ofinputting the irradiation prohibition signal and the irradiationnon-prohibition signal to the irradiation-signal output interface 37 isadopted as the moving-object tracking apparatus 4A, the irradiationcontroller 12 performs irradiation of the radioactive rays R using theradiation irradiation apparatus 5 on condition that the irradiationtiming signal is inputted from the irradiation-signal output interface37.

Although the interlock device 54 is integrally formed with themoving-object tracking apparatus 4A in the second embodiment, theinterlock device 54 and the moving-object tracking apparatus 4A may beseparately provided.

As described above, the moving-object tracking apparatus (the medicalimage processing apparatus) of the second embodiment is characterized inincluding: a first-image input interface configured to acquire a firstimage which is a fluoroscopic image of a patient imaged by using animaging apparatus; a motion-information input interface configured toacquire motion information of the patient which is correlated withmotion of a target portion of the patient to be subjected to radiationirradiation; a specifying processor configured to specify a timingsuitable for the radiation irradiation on the basis of the motioninformation; a feature calculator configured to acquire feature of thefirst image generated by imaging the patient at the specified timing andcalculate a normal range indicative of a range of feature of a normalstate, in which the radiation irradiation is not prohibited, from thefeature; a second-image input interface configured to acquire a secondimage which is a fluoroscopic image of the patient imaged by using theimaging apparatus and is a determination target; an image determinationprocessor configured to perform determination as to whether the featureof the second image is included in the normal range or not; and adetermination-signal output interface configured to output adetermination signal according to the result of the determination.

The moving-object tracking method (medical image processing method) ofthe second embodiment is characterized in including: a first imageacquisition step of acquiring a first image which is a fluoroscopicimage of a patient imaged by using an imaging apparatus; amotion-information acquisition step of acquiring motion informationcorrelated with movement of a target portion of the patient to besubjected to radiation irradiation; a specifying step of specifying atiming suitable for the radiation irradiation on the basis of the motioninformation; a feature acquisition step of acquiring feature of thefirst image generated by imaging the patient at the specified timing andcalculating a normal range indicative of a range of the feature of anormal state, in which the radiation irradiation is not prohibited, fromthe feature; a second-image acquisition step of acquiring a second imagewhich is a fluoroscopic image of the patient imaged by using the imagingapparatus and is a determination target; an image determination step ofdetermining whether the feature of the second image is included in thenormal range or not; and a signal output step of outputting adetermination signal according to a determination result of the imagedetermination step.

In this manner, radiation irradiation in an abnormal state (non-normalstate) can be avoided by determining the image of the regioncorresponding to the specific region included in the second image, whichis generated by imaging the patient P using an imaging apparatus duringradiotherapy, with the use of the feature. In addition, by making theinterlock device 54 perform machine learning of the feature of the firstimages generated by imaging the patient at the time of treatmentplanning using the imaging apparatus, labor for setting the normal rangeat the time of treatment planning can be reduced.

Third Embodiment

Hereinbelow, a description will be given of the moving-object trackingapparatus (medical image processing apparatus) of the third embodimentby referring to FIG. 16 to FIG. 18. The same reference signs areassigned to the same components as the above-described embodiments ineach figure, and duplicate description is omitted. It should be notedthat the moving-object tracking apparatus and the medical imageprocessing apparatus are integrally configured in the third embodiment.

As shown in FIG. 16, the moving-object tracking apparatus 4B of thethird embodiment includes the specific-setting-information generator 53configured to generate the specific setting information and a markerlearning device 63. In the third embodiment, imaging for generating theX-ray images 40 (FIG. 5) and tracking of the marker M are performed onthe basis of the specific setting information generated by thespecific-setting-information generator 53. Further, the otherconfiguration of the moving-object tracking apparatus 4B is almost thesame as that of the moving-object tracking apparatus 4 (FIG. 3) of thefirst embodiment.

In the above-described embodiments, the marker M in a spherical shape isexemplified. However, in actual treatment, the marker M having variousshapes is used according to the site in the body where the marker M isplaced. Additionally, there are various sizes for the marker M. Forinstance, there are a rod-shaped (coil-shaped) marker M with a diameterof 0.5 mm and a length of 5 mm, a marker M in a clip shape, and awedge-shaped marker M.

When the respective markers M having these shapes are imaged usingX-rays, the images of the respective markers M appearing in the X-rayimages 40 differ from each other according to, e.g., orientation of eachmarker M or the posture of the patient P (FIG. 17). For instance, therod-shaped marker M is depicted as a circular image when it is placed soas to be parallel to the normal direction with respect to the imagesurface, and gradually becomes a long bar shape as it is inclined fromthat position. In this manner, in order to detect the position of themarker M appearing in the X-ray images 40 with the tracking processor35, it is preferable to cause the marker learning device 63 to learn theimages of the respective markers M in advance.

The marker learning device 63 includes: a marker-image input interface(i.e., object-image acquisition unit) 66 configured to acquire a markerimage 64 (i.e., object image as shown in FIG. 17A) in which the marker M(learning target) is depicted; a non-marker image input interface (i.e.,non-object image acquisition unit) 67 configured to acquire a non-markerimage 65 (i.e., non-object image as shown in FIG. 17B) in which themarker M is not depicted; a parameter calculator (i.e., parametercalculation unit) 68 configured to calculate parameters of adiscriminator used for identifying the position where the marker M isdepicted in an image, on the basis of machine learning; and a parametermemory (i.e., parameter storage unit) 69 configured to store thecalculated parameters.

In the moving-object tracking apparatus 4B, the X-ray image inputinterface (fluoroscopic-image acquisition unit) 31 acquires the X-rayimages 40 (fluoroscopic images) of the patient (object) P imaged byusing the X-ray imaging apparatus 7 during radiotherapy. Afterward, thetracking processor (position detection unit) 35 detects the position ofthe marker M appearing in the X-ray images 40 by using the discriminatorwhich is represented by the parameters stored in the parameter memory69.

As shown in FIG. 17A and FIG. 17B, a large number of marker images 64and non-marker images 65 are prepared in advance for machine learning.In the respective marker images 64, the markers M in variousorientations and the living tissues 70 are depicted. In each of thenon-marker images 65, the marker M is not depicted and only the livingtissues 70 are depicted. From these marker images 64 and non-markerimages 65, the marker learning apparatus 63 generates a discriminatorfor discriminating between the marker images 64 and the non-markerimages 65 by machine learning. The discriminator may be configured tooutput binary likelihoods (i.e., plausibility) of 0 and 1 indicatingwhether the marker M is included in the image or not. Additionally oralternatively, the discriminator may be configured to output alikelihood of 0 to 1 indicating the same.

It should be noted that the marker images 64 may be images actuallyobtained by X-ray imaging of the patient P. In addition, the markerimages 64 may be an image generated by CG (Computer Graphics) of avirtual image of the marker M. Further, the marker images 64 may be theDRR images 46 generated on the basis of the geometry information of theX-ray imaging apparatus 7 and the three-dimensional volume image of thepatient P in which the marker M is placed. Moreover, the marker images64 may be the X-ray image s40 of the patient P imaged at the time ofrehearsal before treatment or may be the X-ray images 40 of a thirdperson imaged separately from the rehearsal. Furthermore, the markerimages 64 may be the DRR images 46 generated from a three-dimensionalvolume image of a third person.

In addition, the parameter calculator 68 generates a discriminator thatdiscriminates between the marker images 64 and the non-marker images 65by machine learning. The parameter calculator 68 causes the parametermemory 69 to store a parameter group representing the generateddiscriminator as parameters for detecting the markers M.

As the discriminator, an arbitrary supervised learning discriminator canbe used. For instance, a support vector machine, a neural network, and adecision tree can be used as the discriminator. As the neural network, adeep neural network may be used. As the deep neural network, aconvolution neural network may be used. In other words, themoving-object tracking apparatus 4B includes artificial intelligencebased on machine learning.

The tracking processor 35 acquires the parameters stored in theparameter memory 69, and acquires the X-ray images 40 from the X-rayimage input interface 31. Afterward, the X-ray images 40 are inputted tothe discriminator determined by the parameters, and the position of eachmarker M appearing on each X-ray image 40 is specified on the basis ofthe likelihood obtained from the discriminator.

Next, a description will be given of the marker tracking processing(medical image processing method) to be performed by the moving-objecttracking apparatus 4B of the third embodiment with reference to FIG. 18.Since processing of some steps of the marker tracking processing of thethird embodiment is the same as that of the first embodiment, duplicatedescription is omitted.

First, in the step S71 (i.e., marker image acquisition step), themarker-image input interface 66 acquires the marker images 64 (FIG.17A), in each of which the marker M is depicted, before start ofradiotherapy.

In the next step S72 (i.e., non-marker image acquisition step), thenon-marker-image input interface 67 acquires the non-marker images 65(FIG. 17B), in each of which the marker M is not depicted.

In the next step S73 (i.e., parameter calculation step), the parametercalculator 68 calculates the parameters of the discriminator used foridentifying the position of the marker(s) M in the images by machinelearning.

In the next step S74, the parameter memory 69 stores the calculatedparameters.

In the next step S75, radiotherapy using the radiation irradiationapparatus 5 is started.

In the next step S76 (i.e., fluoroscopic-image acquisition step), theX-ray imaging apparatus 7 images the patient P so as to generate theX-ray images 40 of the patient P and then the X-ray image inputinterface 31 acquires the X-ray images 40 from the X-ray imagingapparatus 7.

In the next step S77 (i.e., position detection step), the trackingprocessor 35 detects the position of the marker(s) M appearing in eachX-ray image 40 by using the discriminator which is determined from theparameters stored in the parameter memory 69.

In the next step S78, the tracking processor 35 determines whether thedetected marker M is at the specific position 41 (FIG. 5) or not. Whenthe marker M is not located at the specific position 41, the processingproceeds to the step S80 to be described below. Conversely, when themarker M is at the specific position 41, the processing proceeds to thestep S79 in which the irradiation-signal output interface 37 outputs theirradiation timing signal to the irradiation controller 12 and then theprocessing proceeds to the step S80.

In the step S80, the moving-object tracking apparatus 4B determineswhether the radiotherapy has completed or not. When the radiotherapy hasnot been completed, the processing returns to the step S76 as describedabove. Conversely, when the radiotherapy is completed, the markertracking process is completed.

Although the marker learning device 63 is integrally formed with themoving-object tracking apparatus 4B in the above-described case, themarker learning device 63 and the moving-object tracking apparatus 4Bmay be separately provided in the third embodiment. In the thirdembodiment, a description has been given of the case where the markerimages 64 (i.e., images depicting the marker M) and the non-markerimages 65 (i.e., images in which the marker M is not depicted) are usedas the teacher data at the time of learning for generating adiscriminator which outputs a likelihood indicative of whether themarker M is included in the image or not. However, the teacher data maybe changed depending on what is to be identified by the discriminator.For instance, in the case of generating a discriminator which outputsthe likelihood indicative of whether the marker M is depicted in thevicinity of the center of the image or not, each image in which themarker M appears near the center of the image may be prepared as amarker image 64 while all the other images are prepared as thenon-marker images 65. In this case, the non-marker images 65 includeimages depicting the marker M at the edge of the image and images inwhich the marker M is not depicted.

Although the marker learning device 63 learns images depicting themarker M in order to track the marker M (learning target) forradiotherapy in the third embodiment, this technique may be applied toother embodiments. For instance, this technique can also be applied toprocessing of learning images which depict a guidewire, in order totrack the guidewire (learning target) in catheter treatment.

A catheter is a medical instrument and is a hollow tube. In cathetertreatment, a catheter is inserted into a patient's body (such as insideof a blood vessel and inside of an internal organ), and body fluid isdischarged or a stent balloon for vasodilation is sent. In addition, aguidewire is used for operation of the catheter.

For instance, a guidewire is inserted in the body in advance, and acatheter is advanced by this guidewire. Here, time-sequential X-rayimages of a patient are generated on a real-time basis and the catheteris advanced while the doctor confirms the position of the guidewire withthe real-time X-ray images. Since the guidewire is made of metal, theguidewire appears more clearly than the body tissue in the X-ray imagessimilarly to the marker M of the third embodiment. Since the guidewireis in the shape of a wire, the image of its tip portion is similar tothe image of the rod-shape marker M. Thus, it is possible toautomatically track the position of the tip of the guidewire in theX-ray images by causing the discriminator to perform machine learning ofthe image of the guidewire in a manner similar to the third embodiment.

As described above, the moving-object tracking apparatus (medical imageprocessing apparatus) of the third embodiment is characterized inincluding: an object-image input interface configured to acquire anobject image in which a target object or a virtual image of the targetobject is depicted; a parameter calculator configured to calculate aparameter used for identifying a position where the target object isdepicted in an image, on the basis of machine learning by using theobject image; a fluoroscopic-image input interface configured to acquirea fluoroscopic image generated by imaging an examinee (e.g., patient)provided with the target object using an imaging apparatus; and aposition detector configured to detect a position of the target objectdepicted in the fluoroscopic image on the basis of the parameter.

The moving-object tracking method (medical image processing method) ofthe third embodiment is characterized in including: an object-imageacquisition step of acquiring an object image in which a target objector a virtual image of the target object is depicted; a parametercalculation step of calculating a parameter used for identifying aposition where the target object is depicted in an image, on the basisof machine learning by using the object image; a fluoroscopic-imageacquisition step of acquiring a fluoroscopic image generated by imagingan examinee (e.g., patient) provided with the target object using animaging apparatus; and a position detection step of detecting a positionof the target object depicted in the fluoroscopic image on the basis ofthe parameter.

For instance, in the medical image processing apparatus of conventionaltechnology, it is required to previously register a large number oftemplate images when markers are viewed from various angles and it isalso required to compare these template images with fluoroscopic imagesgenerated by imaging a patient during radiotherapy. In such conventionaltechnology, there is a problem that load of image processing increases.However, in the third embodiment, such a problem can be solved. Inaddition, labor for setting various conditions before radiotherapy issaved by using machine learning.

Although the medical image processing apparatuses of embodiments havebeen described on the basis of the first to third embodiments, theconfiguration applied in any one of the above-described embodiments maybe applied to another embodiment and configurations applied in therespective embodiments may be used in combination. For instance, atleast a part of the interlock processing of the second embodiment or themarker tracking process of the third embodiment may be executed in themedical image processing apparatus or the moving-object trackingapparatus of the first embodiment.

The medical image processing apparatus 3 and the moving-object trackingapparatus 4 of the present embodiment includes a storage device such asa ROM (Read Only Memory) and a RAM (Random Access Memory), an externalstorage device such as a HDD (Hard Disk Drive) and an SSD (Solid StateDrive), a display device such as a display, an input device such as amouse and a keyboard, a communication interface, and a control devicewhich has a highly integrated processor such as a special-purpose chip,an FPGA (Field Programmable Gate Array), a GPU (Graphics ProcessingUnit), and a CPU (Central Processing Unit). The medical image processingapparatus 3 and the moving-object tracking apparatus 4 can be achievedby hardware configuration with the use of a normal computer.

Note that each program executed in the medical image processingapparatus 3 and the moving-object tracking apparatus 4 of the presentembodiment is provided by being incorporated in a memory such as a ROMin advance. Additionally or alternatively, each program may be providedby being stored as a file of installable or executable format in anon-transitory computer-readable storage medium such as a CD-ROM, aCD-R, a memory card, a DVD, and a flexible disk (FD).

In addition, each program executed in the medical image processingapparatus 3 and the moving-object tracking apparatus 4 may be stored ona computer connected to a network such as the Internet and be providedby being downloaded via a network. Further, the medical image processingapparatus 3 and the moving-object tracking apparatus 4 can also beconfigured by interconnecting and combining separate modules, whichindependently exhibit respective functions of the components, via anetwork or a dedicated line.

Although the patient P which is a human being is exemplified as anexamination object in the above-described embodiments, the medical imageprocessing apparatus 3 may be used for a case where an animal such as adog and a cat is the examination object and radiotherapy is performed onthe animal.

Although the respiration of the patient P is monitored by using therespiration sensor 11 in the above-described embodiments, therespiration of the patient P may be monitored in another mode. Forinstance, the respiration of the patient P may be monitored by attachinga reflective marker configured to reflect infrared rays to the bodysurface of the patient P, irradiating the reflective marker with aninfrared laser, and acquiring the reflected wave.

In the above-described embodiments, the medical image processingapparatus 3 displays the X-ray images 40 of the patient P imaged duringrehearsal and a user performs selection of the marker M, change of thespecific range 45, or change of the specific position 41. However, themoving-object tracking apparatus 4 may be configured such that a usercan select the marker M, change the specific range 45, or change thespecific position 41 during rehearsal.

Although the plural markers M are placed in the body of the patient Pand these markers M are tracked by X-ray imaging in the above-describedembodiments, embodiments of the present invention are not limited tosuch an aspect. For instance, only one marker M may be placed in thebody of the patient P and be tracked by X-ray imaging.

Although two pairs of the X-ray irradiators 9 and the X-ray detectors 10are provided in the above-described embodiments, the marker M may betracked by using only one pair of the X-ray irradiator 9 and the X-raydetector 10. Further, the marker M may be tracked by usingtime-sequential X-ray images, each of which is acquired by imaging thepatient P from three or more directions with the use of three or morepairs of the X-ray irradiators 9 and the X-ray detectors 10.

Although the specific setting information is generated by generating theDRR images 46 and specifying the position where the marker M appears inthe above-described embodiments, the specific setting information may begenerated without generating the DRR images 46. Since the informationnecessary for generating the specific setting information is theposition of the marker M, the specific setting information can begenerated when the three-dimensional volume image and the geometryinformation can be acquired.

In the above-described embodiments, a description has been given of thecase where the medical image processing apparatus 3 or the moving-objecttracking apparatus 4 includes a monitor (i.e., display unit) fordisplaying images such as the X-ray images 40 and the DRR images 46.However, the medical image processing apparatus of each embodiment maybe configured as the medical image processing apparatus 3 whichgenerates and outputs the specific setting information so that themonitor can be omitted.

Although a mode in which each step is executed in series is illustratedin the flowcharts of the present embodiment, the execution order of therespective steps is not necessarily fixed and the execution order ofpart of the steps may be changed. Additionally, some steps may beexecuted in parallel with another step.

According to the above-described embodiments, it is possible to savelabor of a user related to setting of imaging for generating an imagedepicting a marker or setting of image processing of this image, byproviding a specific-setting-information generator which generatesspecific setting information used for the setting of imaging forgenerating the image depicting the marker or the setting of imageprocessing of this image on the basis of three-dimensional volume imageand geometry information.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made without departing from the spiritof the inventions. The accompanying claims and their equivalents areintended to cover such forms or modifications as would fall within thescope and spirit of the inventions.

What is claimed is:
 1. A medical image processing apparatus comprising:a first input interface configured to acquire at least onethree-dimensional volume image of an object which is provided with atleast one marker, the three-dimensional volume image being generated byimaging the object using a medical examination apparatus; a second inputinterface configured to acquire geometry information of an imagingapparatus which is used for imaging the object to generate afluoroscopic image of the object; and a specific-setting-informationgenerator configured to generate specific setting information based onthe three-dimensional volume image and the geometry information, thespecific setting information being used for setting of imaging forgenerating an image depicting the at least one marker or setting ofimage processing of the image depicting the at least one marker; whereinthe specific setting information includes information for setting aspecific range in at least one of the fluoroscopic image and at leastone digital reconstructed radiograph generated based on thethree-dimensional volume image, the specific range being indicative of arange where the at least one marker is depicted in an entire range ofthe at least one of the fluoroscopic image and the digital reconstructedradiograph.
 2. The medical image processing apparatus according to claim1, wherein the at least one three-dimensional volume image comprises aplurality of the three-dimensional volume images, the at least onedigital reconstructed radiograph comprises a plurality of the digitalreconstructed radiographs, the first input interface acquires theplurality of the three-dimensional volume images, and thespecific-setting-information generator generates the specific settinginformation based on a plurality of the digital reconstructedradiographs generated using the respective plurality ofthree-dimensional volume images.
 3. The medical image processingapparatus according to claim 1, further comprising: an image generatorconfigured to generate the digital reconstructed radiograph based on thethree-dimensional volume image and the geometry information; and areconstructed-image monitor configured to display a range indicationindicative of the specific range in such a manner that the rangeindication is superimposed on the digital reconstructed radiograph. 4.The medical image processing apparatus according to claim 1, furthercomprising: a fluoroscopic-image monitor configured to display a rangeindication indicative of the specific range in such a manner that therange indication is superimposed on the fluoroscopic image.
 5. Themedical image processing apparatus according to claim 1, furthercomprising: a range input interface configured to receive an instructionto modify the specific range; and a range changer configured to changethe specific setting information based on the instruction received bythe range input interface.
 6. The medical image processing apparatusaccording to claim 1, wherein the specific setting information differsdepending on a respiratory state of the object which is acquired byusing a respiration monitoring apparatus configured to monitorrespiration of the object.
 7. The medical image processing apparatusaccording to claim 1, wherein the at least one marker comprises aplurality of markers which are provided with respect to the object; andthe specific setting information includes information for setting atleast one marker among the plurality of markers as a target of imageprocessing.
 8. The medical image processing apparatus according to claim1, further comprising a selection input interface and a marker setter,wherein the at least one marker comprises a plurality of markers whichare provided with respect to the object; the selection input interfaceis configured to receive an instruction to select at least one markeramong the plurality of markers as a target of image processing; and themarker setter is configured to set the specific setting informationbased on the instruction received by the selection input interface. 9.The medical image processing apparatus according to claim 1, furthercomprising a third input interface configured to acquire positionalinformation of the at least one marker based on the three-dimensionalvolume image, wherein the specific-setting-information generator isconfigured to generate the specific setting information by using thepositional information of the at least one marker.
 10. The medical imageprocessing apparatus according to claim 1, wherein the specific settinginformation includes information for setting a specific positiondefining a condition under which a radiation irradiation apparatusradiates radioactive rays; and the condition is that the radiationirradiation apparatus radiates the radioactive rays when the marker ispresent at the specific position.
 11. A medical image processing methodcomprising: a first acquisition step of acquiring at least onethree-dimensional volume image of an object which is provided with amarker, the three-dimensional volume image being generated by imagingthe object using a medical examination apparatus; a second acquisitionstep of acquiring geometry information of an imaging apparatus which isused for imaging the object to generate a fluoroscopic image of theobject; and a specific-setting-information generation step of generatingspecific setting information based on the three-dimensional volume imageand the geometry information, the specific setting information beingused for setting of imaging for generating an image depicting the markeror setting of image processing of the image depicting the marker;wherein the specific setting information includes information forsetting a specific range in at least one of the fluoroscopic image andat least one digital reconstructed radiograph generated based on thethree-dimensional volume image, the specific range being indicative of arange where the at least one marker is depicted in an entire range ofthe at least one of the fluoroscopic image and the digital reconstructedradiograph.
 12. A non-transitory computer-readable medium storing amedical-image processing program that allows a computer to perform: afirst acquisition process of acquiring at least one three-dimensionalvolume image of an object which is provided with a marker, thethree-dimensional volume image being generated by imaging the objectusing a medical examination apparatus; a second acquisition process ofacquiring geometry information of an imaging apparatus which is used forimaging the object to generate a fluoroscopic image of the object; and aspecific-setting-information generation process of generating specificsetting information based on the three-dimensional volume image and thegeometry information, the specific setting information being used forsetting of imaging for generating an image depicting the marker orsetting of image processing of the image depicting the marker; whereinthe specific setting information includes information for setting aspecific range in at least one of the fluoroscopic image and at leastone digital reconstructed radiograph generated based on thethree-dimensional volume image, the specific range being indicative of arange where the at least one marker is depicted in an entire range ofthe at least one of the fluoroscopic image and the digital reconstructedradiograph.
 13. A moving-object tracking apparatus comprising: aspecific-setting-information input interface configured to acquire thespecific setting information from the medical image processing apparatusof claim 1; an image input interface configured to acquire thefluoroscopic image; and a tracking processor configured to perform imageprocessing of tracking a position of the at least one marker by usingthe specific setting information, the at least one marker being providednear a target portion of radiation irradiation in the object and beingdepicted in a plurality of fluoroscopic images which are generated byserially imaging the object using the imaging apparatus.
 14. Themoving-object tracking apparatus according to claim 13, furthercomprising a warning output interface configured to output a warningsignal when there is a possibility that tracking of the at least onemarker has failed.
 15. A radiation therapy system comprising: themedical image processing apparatus of claim 1; the imaging apparatusconfigured to generate a plurality of fluoroscopic images of the objectby serially imaging the object; a moving-object tracking apparatusequipped with a tracking processor configured to perform imageprocessing of tracking a position of the at least one marker which isdepicted in the plurality of fluoroscopic images of the object generatedby the imaging apparatus; a radiation irradiation apparatus configuredto radiate radioactive rays used for treatment onto a target portion ofradiation irradiation in the object when the at least one marker trackedby the moving-object tracking apparatus exists at a specific position,wherein at least one of the imaging apparatus and the moving-objecttracking apparatus is controlled by using the specific settinginformation generated by the medical image processing apparatus.